It is often desirable to form a seal with an inside wall of an opening or a tube. This may be done to completely block or plug the opening or tube or to connect an adapter or similar structure to the opening or tube. For example, one method of filling a vehicle radiator requires establishing a partial vacuum in the radiator. This is done by inserting an adapter into the radiator filler neck, forming a seal between the adapter and the inside wall of the filler neck and using a pump to remove air from the radiator through the adapter. An opening in the adapter is then connected to a source of clean radiator fluid, and the pressure difference between the inside of the radiator and ambient pressure forces the clean radiator fluid into the radiator.
Conventional adapters for filling vehicle radiators generally include a flexible seal member that is insertable into the radiator filler neck, a shaft that extends through the flexible seal member, and two bodies at one end of the seal member that are connected to one another by screwthreads. The shaft is connected to one of the bodies, extends through the other body and the seal member and is connected to the seal member. Starting with the two bodies screwed together, the flexible seal member is inserted into the filler neck, and the bodies are then screwed apart from one another. This moves the top of one body away from the bottom of the other body, pulls the distal end of the shaft toward the bodies and compresses the seal member. Such compression of the seal member causes the side wall of the seal member to bulge and press against the inside wall of the tube. As the bodies are unscrewed further, the connection between the sidewall and the seal member becomes tighter, and a fluid-tight seal with the tube sidewall is formed.
This arrangement works adequately for its intended purpose. However, in order to expand the seal member sufficiently to form a tight seal with the inside wall of the filler neck, it is generally necessary to turn the one body multiple times in one direction with respect to the other body to form the seal and then to turn the one body multiple times in the other direction to reverse this process. It would be desirable to provide a device that forms a seal with the inside of an opening or tube in a manner that does not require this screwing operation and that can be sealed to and unsealed from the interior of an opening or a tube in a simple manner.